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SQL*Debug
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Debugging PL/SQL by printing debug messages into a
windows program. |
SQL*Debug
is a PL/SQL debugger. It prints debug messages from PL/SQL into a windows program. You can call SQL*Debug
from anywhere in pl/sql using the following syntax:
OraDebug.debug( 'your text goes here' );
With the SQL*Debug windows program you register for debug messages from a particular session. If no SQL*Debug
program is listening for messages, the debug messages are simply not generated. Therefore no performance degradation
occurs when calling SQL*Debug.debug.
Apart from the ad-hoc debug session you can use SQL*Debug to monitor your PL/SQL packages. You can code for
each public function or procedure a general exception handler where you call SQL*Debug:
begin
do_work;
exception
when
others then
OraDebug.debug('Error in
mypack.myproc:' || sqlerrm(sqlcode)
);
raise; --propagate the
error
end; |
The reason why this use of SQL*Debug is so valuable is that the above code does not degrade performance. If
nothing unexpected goes wrong, SQL*Debug is not executed. If a user experiences problems you can point the SQL*Debug
windows program to the user's session and see the error messages come to your screen. To demonstrate this consider
the following example:
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I've logged in as SCOTT and execute the following pl/sql. Note that this sql may have also been
e.g. a package, trigger or even a Forms library!.
I make the deliberate mistake loading about 20 characters into a varchar buffer of
length 3.
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Use SQL*Debug to choose the session you want to see the debug messages for.
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In the SQL*Debug main program you see that the error message appears in the log.
Each item is timestamped (day-month hour:min:ss:ms) and the time is calculated
between the messages, giving you some feel for
performance.
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